The top materials for CNC plastic machining are ABS, Nylon, Polycarbonate, POM, PEI, and PTFE, each chosen for its unique properties such as strength, flexibility, and heat resistance
ABS Plastic
ABS or Acrylonitrile Butadiene Styrene belongs to the category of materials commonly used for CNC machining, as such materials combine their properties in most favorable ways to make CNC machining suitable for a broad range of applications. Typically associated with toughness, high impact resistance, and pleasing aesthetics, ABS material is favored in both prototyping and end-use production.
Physical and Mechanical Properties
ABS combines the toughness of polybutadiene rubber with the strength and rigidity offered by the acrylonitrile and styrene polymers, with the tensile strength typically around 4,300 psi. The resulting material displays excellent toughness and impact strength when under harsh handling and mechanical stress and does not fracture.
Machining and Finishing
The perfect combination of properties makes CNC machining easy and aesthetically pleasing to work with, as it may be cut, turned, drilled, and milled with contour precision. This feature makes ABS a perfect choice for parts that need to be fitted into each other and displayed in automotive, consumer electronics, and toy industries, to name a few.
Temperature and Chemical Resistance
ABS may become quite soft and finally deform at or above 176°F , which is not considered abnormal for a material used in car interiors and household appliance casings, covers, and the outer handles of suitcases and bags; however, when molded using the pressure heat mode, it may acquire rigidity not much lower than that associated with high impact polystyrene. ABS also offers solid resistance to a number of chemicals, organic and inorganic, mineral and organic acids, and the vast majority of alkalis; with its properties, ABS is an excellent choice for manufacturing pipes or lining tanks or anything that involves abrasive materials.
Application in Industry
Finally, an example of an industrial application of this plastic is the manufacture of LEGO bricks. The material should have a very precise shape to fit perfectly into any other piece of any color and texture.
Market Survey
The automotive industry produces ABS dashboard interior and other trim for two reasons. The first and possibly most important can be the nature of this plastic that is sturdy enough for such use, but maintains a lighter weight than other materials used in a similar way. The second is that it may be heated and molded in complex parts of high surface quality, both as functional parts and as an aesthetic means.
Nylon
Nylon is another most used CNC plastic machining material, thanks to superior strength and elasticity. The two primarily used forms of Nylon are Nylon 6 and Nylon 6/6, which find their use in a variety of industrial applications. Some of these uses are a result of the molecular structure of the polymers used in these two forms of Nylon.
Mechanical Strength and Toughness
Nylon is considered to be a material that possesses high tensile strength, ranging from about 7,000 to 24,000 psi. Consequently, this material is used in many parts that need to be able to bear the stress, especially when these parts encounter different types of impact. The property of flexibility of Nylon allows it to not undergo plastic deformation because the material absorbs the impact energy.
Heat and Chemical Resistance
Nylon melts at an approximate temperature of 428°F and retains its structural characteristics throughout a wide temperature range. This means that Nylon can be used in many applications because of its heat resistance as such. In addition to that, Nylon can resist a number of dynamic and abrasive forces of physical and chemical nature. In a word, Nylons resistance to wear and abrasion is excellent. This material is considered intrinsically durable by withstanding various oils, greases, and fuels chemical spills. For instance, under-the-hood automotive applications of Nylon and Nylon gears and bearings in mechanical uses.
Moisture Absorption and Its Impact
Nylons feature which makes it be able to be able to absorb moisture is considered a weakness in some applications. That is, the ability of Nylon to undergo moisture absorption can cause dimensional variation. While this is a definite disadvantage in some applications like jigs and fixtures, in other applications the toughness and resistance to fracture under hydrostatic loading can be improved. Consequently, in some precise applications, the parts can be conditioned prior to processing to a stable moisture content. This provides consistent and repeatable dimensional characteristics.
Common Uses in Industry
The material is used in the electronics industry to make insulating materials and, due to excellent self-lubrication qualities, some mechanical parts do not have to be lubricated with other substances as well. These help reduce the cost of maintenance as well as increase the longevity of the parts. However, careful consideration of the parameters for cutting is essential so that the material does not melt or be damaged by the heat that is produced by the tooling. Using sharp tools, proper cooling methods can help maintain the accuracy of the machining process.
Polycarbonate
Polycarbonate can be considered the most distinguishable in the CNC machining world for the bigger impact resistant property and clarity of the material. Such properties have made it a favored material for a variety of heavy-duty applications. Polycarbonate features include:
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Polycarbonate is most known for its impact resistance. Majority of other plastics feature around an approximately 900 psi tensile strength whereas polycarbonate is around 9,500 psi. This material has superior impact strength that allows it to survive being hit regularly and never breaks under normal use. This feature makes it ideal for safety gear, bullet proof glass, and other disaster equipment.
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Another property of polycarbonate is high optical clarity. The material allows glasses to transmit light almost as well as glass can and it is used in eyewear, transparent covers, and lighting fixtures that can require high light-to-cover conversion. Polycarbonate has also been found to block UV light; this feature makes it ideal for outdoor applications.
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Polycarbonate has a temperature range of -40°F to 280°F (-40°C to 138°C). Its thermal-stability and flame-retardance allows its use in different temperatures in applications such electrical/electronics where there are fluctuating temperatures.
Machinability polycarbonate
Correct feed rates and cutting speeds together with the proper use of coolants aids the maintenance of the integrity and finish of polycarbonate material. Such correct parameters prevent the polycarbonate material from melting or char due to the material’s sensitivity to high temperatures.
Industry applications
In the automotive world, polycarbonates are found on headlamp lenses and dashboard parts due its strength and high light transmitting materials. In the air-craft world, it is used in various parts of the cockpit and transparent enclosures where both potential of a clear view and impacts are likely to occur. Examples and market adaptation. Companies such as Bayer and GE have developed polycarbonate types for engineering applications that required precision machining and high-quality finishes. Their polycarbonate materials will be machined without such flaws as cracks and stress marks.
Polyoxymethylene
One of the most popular materials for CNC machining is polyoxymethylene , more commonly known as Acetal or by its brand names such as Delrin. It is valued for its mechanical properties including high precision, stiffness, and excellent wear resistance.
High Dimensional Stability and Precision
POM is characterized by unusually high dimensional stability. When it comes to producing complex parts requiring tight tolerance, it can often be held within ±0.005 inches. This property means it is ideal for use with precision mechanical assemblies, where components should fit and interact with one another without the need for adjustments during or after the machining process.
Wear and Friction Properties
The natural lubricity of POM makes it suitable for use in products, especially components in automotive technology involving moving parts. It has a low level of friction, so it is excellent for use in gears of all kinds, from simple planetary gears to complex helical designs. POM is wear-resistant and can be used to make bearings, bushings, and sliding components to minimize the wearing forces between machine parts, make the product longer-lasting, and reduce the recurrence of maintenance.
However, some sources believe that the material is not ideal for high-speed moving components ridden with vibration and impact as they might shatter if enough stress is applied. These are rare cases, as such use is frowned upon due to the poor energy absorption of POM.
Chemical Resistance
POM is very resistant to a wide range of chemicals, including many solvents, and can be used to produce automotive fuel systems. It is also stable in an environment where chemical exposure is ubiquitous.
Lower Moisture Absorption
In addition, unlike many other plastics, POM exhibits extremely low moisture absorption. This makes it very stable in wet environments and further enhances its moisture resistance.
Thermal Properties
POM is thermally stable, with its melting usually occurring at about 347°F . This allows it to be used under conditions that are challenging for many other plastics.
Industrial and commercial use
All these characteristics make POM a popular choice in CNC machining. Its applications are mostly found in the automotive industry, where the material is used to make fuel systems parts, door handles, and other assemblies. The properties of the material are also useful in producing electric or electronic devices and appliances with repeated mechanical actions or increased contact with various substances.
Processing and machining tips
While machining POM, one should remember to use sharp, fine blades to prevent the material from melting and achieve a clean cut. It is also important to provide sufficient cooling as POM can melt if not cooled down.
Polyetherimide
Polyetherimide commonly known by its trade name Ultem, is an excellent option for CNC machining owing to the material’s exceptional heat resistance, mechanical robustness, and excellence as an electrical insulator. When opting to CNC machine PEI, it is important to utilize techniques that reduce the material’s thermal degradation. Its main applications include:
Industrial Applications
In the aerospace industry, the material is used for interior components like wall panels and cabin dividers because its heat resistance is matched by low smoke and toxicity profiles. In the automotive industry, it is applied in high-performance parts owing to its thermal stability and impressive mechanical capabilities.
Coolant
When working with PEI, it is important to use tools that will help dissipate the heat that will be generated. The cooling strategies and tooling approach will determine how effective the process will be. Being resistant to 340°F (171°C), and having a glass transition temperature of about 419°F (215°C), one approach that is effective at managing heat is through use of coolant strategies. It typically has a tensile strength of upto 15,200 psi which is impressive. This coupled with its excellent insulative properties, reflecting an excellent 830 volts/mil dielectric strength, it is a material that is often used for electronic connectors and other electrical components.
The material has also been noted to have great resistance to a vast majority of chemicals ranging from automotive fluids to fully halogenated hydrocarbons and alcohol. The absence of moisture absorption in the material also adds to its outstanding strength retention that is characteristic of dimensional stability in different environments.
One of the unique qualities of PEI relates to its biocompatibility. As such, it can be used in medical devices that will require multiple sterilization processes. The material is resistant to radiation, gamma, steam autoclaving and dry heat, allowing it to be used in scientific instruments like chambers, gaskets, casings and reusable medical devices.
PTFE
Introduction: PTFE, also known as Teflon, is a material used in CNC machining because of its excellent resistance to chemicals and high heat. It is a highly durable, versatile, and efficient material used in many industries for different purposes.
Unique Features
This material can resist such chemicals as acids, bases, and organic solvents. PTFE can be used in the chemical processing industry for that reason. An advantage of that particular trait is that the material will not degrade over time, even if exposed to the harsh environment, keeping its condition and shape undistorted.
According to Matmatch, the melting point of PTFE is at 621°F or 327°C. Hence, preeing a temperature that would distort the material or cause damage is difficult. In other words, the material can handle extreme heat. It is useful in the automotive manufacturers and other, similar industries, where high temperatures are common.
Another benefit is the material’s coefficient of friction. PTFE has one of the lowest friction coefficients compared with other materials. As a result, it can be used in applications that require non-adhesive properties. Besides, it is useful when the application demands very low resistance, such as for mechanical, non-lubricated bearing devices.
Applications
Due to its variety of properties, PTFE is used in multiple industries. The material can be used in the aerospace industry, for example, for manufacturing seals and gaskets that can handle extreme temperatures and irregular pressure distributions in the engines. In the electronics industry, it can be used as a cable and connector sheathing material for its powerful dielectric PTFE properties. PTFE is also used to make surgical implants, used in medical technology as prosthetics and other implants for its inert properties. It is used in the household for making things such as frying pans, where the non-stick qualities of the material make cooking easier.
